This invention relates to an apparatus for applying a label to an article and more particularly to such an apparatus of the so called blow applicator type in which a self adhesive label is applied to an article by means of pressurised gas which is usually supplied as a jet or blast.
Known such apparatus comprise an applicator surface comprising a plurality of, usually through, openings to at least selected ones of which pressurised gas may selectively be applied. The labels are conventionally stripped from a backing, fed onto the applicator surface and retained on the applicator surface, with the self adhesive surface facing away from the applicator surface, by establishing a negative pressure i.e. suction, which is applied through other openings e.g. slots in the surface, the effect of the suction being overcome when the pressurised gas is applied to the openings to propel the label.
One prior proposal is disclosed in GB-A-2078668 but in this proposal suction/pressurised gas is transmitted to an applicator surface from a vacuum/pressurised gas chamber, via pins, the positions of which can be varied to obtain optimum performance.
Known such apparatus operate reliably provided that the distance from the applicator surface to the article is within a small range, but as this distance is increased it is increasingly difficult to ensure that the labels are reliably applied. There is a requirement for such labels to be applied in generally consistent positions to each of a plurality of similar articles as well as for labels each to reach the articles in an appropriate orientation. Typically, the distance from applicator surface to article over which labels have reliably been applied, has not been more than 30 mm.
However there is a requirement for a label applicator apparatus which is able to propel labels reliably over greater distances.
According to a first aspect of the invention we provide an apparatus for applying a label to an article comprising an applicator means having an applicator surface, means to establish a negative pressure at the applicator surface, a plurality of openings to the applicator surface, means to deliver pressurised gas to the openings or a selected set of the openings, characterised in that the applicator means comprises a label receiving member spaced from the applicator surface and comprising a plurality of apertures, means to feed a label onto the label receiving member at which the label is maintained by the negative pressure established at the applicator surface and when the pressurised gas is delivered to the openings in the applicator surface, the gas passes into the space between the applicator surface and the label receiving member, and through the apertures therein to propel the label towards the article.
It has been found that an apparatus according to the invention is able more reliably to propel labels over greater distances than has hithertofore been attainable. In a prototype apparatus labels were reliable propelled over distance of at least 75 mm.
It is believed that by spacing a label receiving member away from the applicator surface, the force applied to the label by the pressurised gas is maximised.
Preferably the apertures in the label receiving member are of a size such that the flow of pressurised gas through the label receiving member is substantially unimpeded, and for examples only, the label receiving member may comprises a wire mesh or apertured plate. Also preferably, there is provided a side closure means to close the space between the applicator surface and the label receiving member.
This not only substantially prevents the flow of pressured gas from the space other than through the apertures of the label receiving member, but also, as with conventional apparatus, a label may be retained prior to application onto an article by suction, and the side closure means improves the suction effect. For example in the apparatus of the invention the applicator surface may comprise slots, and means may be provided to establish a negative pressure through the slots.
The suction achieved may thus be of sufficient strength to maintain a label on the label receiving member when fed onto the label receiving member, until the pressurised gas propels the label towards the article.
Typically the label applying apparatus includes means to print information on the labels just prior to the labels being applied to the articles.
According to a second aspect of the invention, we provide a method of applying a label to an article using an apparatus comprising an applicator means having an applicator surface, means to establish a negative pressure at the applicator surface, a plurality of openings to the applicator surface, means to deliver pressurised gas to the openings or a selected set of the openings, characterised in that the method comprises feeding the label onto a label receiving member which is spaced from the applicator surface, the label receiving member comprising a plurality of apertures, maintaining the label on the label receiving member by means of the negative pressure established at the applicator surface, delivering the pressurised gas to the openings in the applicator surface such that the gas passes into the space between the applicator surface and the label receiving member, and through the apertures therein to propel the label towards the article.
The method may include maintaining the label on the label receiving member until propelled onto the article by the pressurised gas, by applying suction through the applicator surface.